Epidemiology and

Public Health

Introduction, Part II

Changing Patterns of Community Health

• Health patterns in constant state of flux

• Infectious versus chronic diseases

• Population and age-related

Chain of Infection

• Etiological agent

• Source/Reservoir

• Portal of exit

• Mode of transmission

• Portal of entry

• Susceptible host

Modes of Transmission

• Contact transmission

• Vehicle transmission

• Vector transmission

Classes of Epidemics

• Common source (vs. sporadic)

Point sourceIntermittent ContinuousPropagated

Your Assignment: Define these terms

& identify which apply to the following

three graphs

Disease Investigation

• Establish diagnosis

• Identify specific agent

• Describe according to person, place and time

• Identify source of agent

• Identify mode of transmission

• Identify susceptible populations

Epidemiology and Clinical Practice

• Clinical practice dependent on epidemiology

• Epidemiology defines natural history of disease

• Even descriptive information is useful

The Epidemiologic Approach

• Multistep process

• First - determine association

• Then prove causation

• Not all associations are causal

• Examine validity, false assumptions-e.g. - fluoride in water

Analytic Studies

• Type of study

• Design

• Analysis of data

Epidemiology and Prevention

• Identify high risk populations

• Modify risks

• Prevent exposures

Levels of Prevention

• Primary

• Secondary

• Tertiary

Levels of Prevention (cont’d)

• Primary

Involves halting any occurrence of a disease or disorder before it happens

Levels of Prevention (cont’d)

• Secondary

Health screening and detection activities

Levels of Prevention (cont’d)

• Tertiary

Retard or block the progression of condition